IT200 wont kick

[yamit85]

Hi All,
I'm looking for advice on my old IT200. The thing was running awesome last year and I got out for a couple of wednesday rides early season and did loads of riding out with the kids. The thing cut out when I left it idling against a tree while I pulled my kid out of a ditch, then wouldnt start until I put a new plug in it even though the old one looked fine. A couple of rides later, it cut out on a long gentle downhill stretch with a nearly new plug while i was gunning it. I pulled the plug and it looked fine. I put in a new plug and havn't been able to start it since. When I got the thing back home, I went over electrical connections and all looked good but the stator coil was giving half the resistance. Thinking this was the problem - (probably wasn't helping), I swapped out the stator coil. The thing still wouldn't start so I pulled the carb apart and cleaned everything. Carb is back and still nothing. Fresh gas, still nothing. I am getting a healthy looking spark when I kick the motor over. I had a timing light on the thing turning the crank with a drill and the timing looks good so the rotor hasn't spun. I measured compression and it was not too shy of what the manual states, a tad on the lower end of the range but nothing stupidly low. Funny thing is, I could only get a couple of feint pops using starter spray and kicking like a nutter. My next plan is to pull the head off and check for a hole in the piston, stuck rings or whatever but I would have thought that would have shown up in compression.

So I am appealing to those with years of 2 stroke experience especially on old Yamaha ITs to put me out of my misery and point me in the right direction

Thanks
ps Reeds look good.

[cedric]

Thosw bikes came with stupid rich jetting which leads to the fouled plugs. This is compounded by the elevation here to some extent too.

If you have spark, compression and fuel, it has to run. One of those things is missing. Are you sure the pilot jet is clear?

[yamit85]

Thanks Cedric,

Yes, I even dumped the carb in an ultrasonic bath. I intend to strip it again just in case there was sludge in the fuel tank or I missed something. It was a new Clark tank though and I washed it out before using it.

[AJRJ]

Sometimes stuff like this can be tough. Know anyone with a similar bike, and swap a few parts? The fact that it won't catch on starting fluid is probably a sign. Coil good? I've seen coils that failed when hot. What do the reeds look like? You may have cracked/chipped one. That will make the bike tough to start. I believe some of these Yamahas were known for weak ignitions. If it has fuel, it'll run. If you are careful, and your airbox is clean, a squirt (think plastic ketchup container) of fuel will show lots.

I'd check the reeds (free) first.

[yamit85]

Thanks AJRJ,

Ignition coil is good, I changed that out when I put a new charge coil on the stator. Spark looks good. I 'll follow your advice and give a liberal squirting of fuel into the intake. At least if I can get it to pop, I can eliminate the ignition as a problem. Would bad crank seals cause this. Do they go bad suddenly or do they go bad gradually. It wasnt surging or revving out when it was running but did kick out a fair bit of smoke (clutch side CS??) but I just assumed that was the rich running and switched out to a good ester based oil and ran it at 40:1 instead of 25:1 which improved emissions a little

Anyway plan is to double check carb as per Cedrics suggestion and maybe replace the jets completely as they are bound to be well worn after 30 years service. I'll also toss more fuel in the hole

Thanks for the suggestions

[AJRJ]

Definitely a bad crank seal could be part of the issue. I'm sure on a bike that old new ones definitely wouldn't hurt. I've successfully used the screw method to remove and replace without splitting the cases, not sure if that works on an IT though...

If you can get it to fire, you'll be able to eliminate a lot of possibilties.

BTW, back when I used to snowmobile lots, it wasn't uncommon to get several bad plugs in a box. We used to joke that someone dropped the box. A known good plug (maybe even still hot) can help a weak ignition out if you eliminate reeds, seals etc. Compression tests are subjective, If you don't know when the top end was done, just do one. A sure sign of low compression is hard starting. On bikes like this it's common to have two or three or four small issues, each minor, but combined they prevent it from running, or running well.

Or just tell your wife/girlfriend you want to buy Zeals 250 XCF

[Dakota_c69]

Or just tell your wife/girlfriend you NEED to buy Zeals 250 XCF

There fixed it for you...

[yamit85]

Thanks AJRJ
I was hoping not to have to do any serious work but looks like new seals are on the cards. I'm not going to ditch the IT yet as it was a blast to ride when it was running and its kinda different so its worth the effort and expense. Yes the XCF sounds appealing. Maybe if I sell the IT for parts on ebay, I couldbuy a real bike.

[schwang]

Clogged spark arrestor possibly ?

[yamit85]

Yeah, I should probably explain how cheap I am. The spark arrestor is a fine sink strainer on the end of the muffler in a rubber clamp. Theres a bit of discoloration but no clogging. Thanks for the suggestion tho

[trailguy]

Schwang may not be far off. You may have a broken muffler core. I had a Can-Am 125 that broke the muffler core where it meets the stinger inside the muffler can, it shifted sideways and blocked the exhaust flow,the bike barely ran and was hard to start. This could be why your bike seems to want to fire but won't run. Same effect as when trying to start your bike with the muffler plug still in - not that any of us have ever done that.

[boland]

Same effect as when trying to start your bike with the muffler plug still in - not that any of us have ever done that.

You're supposed to take that out? I thought whoever shoots theirs the farthest gets to pick the trail

[yamit85]

I took a MAP torch to the expansion chamber to burn out any spooge - smoke came out both ends. The can looked clear and its just a straight through with a can to hold the packing. You could be right though, i'll see if it will kick without the pipes

Thanks

[Brass]

You said the compression is a couple points low from what the manual says?

Try this just for giggles; pull the spark plug and bring the piston up to top dead center then add about 1/2 a teaspoon of oil, like a 15w40. Then immediately reinstall the plug and try to start it.

The oil will help seal the rings/piston and increase the compression. If the bike starts, you've found the problem (or at least a component of the problem). If it doesn't start you keep looking. Total cost was .03c worth of oil and 5 minutes. (you said you were cheap!).

A 2t needs healthy compression to create proper crankcase pressure and vacuum for the reeds. So if your compression is a bit low, and your reeds are a bit weak, your motor won't run.

When you're done, pull the spark plug and give it a shot of brake cleaner to clear off the oil so it doesn't carbon up when you eventually get the bike running or foul up when trying to start it, if the experiment failed.

Good luck

[yamit85]

Thanks Brass,
Definately worth a shot and CHEAP
Waiting for the next warm spell to try stuff, too cheap to heat the garage